Spring-scale



H. F. DUNN.

SPRING SCALE.

1,369,090' -APPLICATION FILED APR I0. I9l9. Patented 22 2 SHEETS-SHEET 2MW@ W7@ UNITED -s'rares PATENT OFFICE. i

AHENBY' F. DUNN, 015' INDIANAPOLIS, INDIANA, ASSIGNR T0 TOLEDO SGALECOM- PANY, 0F TOLEDO, GEIQ. .A CORPORATIGN ,0F NEW JERSEY.

PRIANGr-SCALE.

Specication of Letters Patent.

Original application led May 10, 1918, Serial No. 95,509. Divided andthis application led April 10, 1919. Serial No. 238,926.

To att 'wim/m @may concern.:

Be it known that I, HENRY F. DUNN, a .citizen of the United States,residing at Indianapolis, in the county of Marion and State of indiana,`have invented cert-ain new and useful Improvements in Spring-Scales, ofwhich the following is a specification.

This invention relatesto improvements in weighing scales, and moreparticularly to that type of scales in which the elongation andcontraction of a Y spring or springs is relied upon to counteract theweight of a commodlty placed upon the scale platform. It is well knownthat the tension of a spring, particularly a coil spring, varies withthe rise and fall of the/ surrounding atmospheric temperature. Forexample, the tension of such lspring weakens with a rise in thetemperature fromv the normal degree of temperature at which the scale isadjusted, and the change and consequent weakening of the tension of theweighing springs is caused by the elongation and expansion of the wirein said springs and by the fibers of the metal becoming more or less'elastic. As a consequence of these changes the weighing accuracy of aspring scale is constantly impaired and rendered unreliable. and the useofy spring scales is objectionable on this account. To obviate thisserious defect in this class of scales is the principal object of thisinvention. To this end the invention consists in adding to the .usualload-counterbalancving springs of a Scale a ,compensating abutmentspring. the tension of which under temperature changes increases ordecreases inversely to that of the load-counterbalancing springs, and soarranging the abutment sprlngs between a fixed support and one end f ofthe weighing springs as to provide means for automatically adjusting theposition of the weighing springs to regulate the tiexure of such springsunder load in accordance l with the prevailing temperature.

p Other objects and advantages will readily appear from the followingdescription, in

`which reference is had to the accompanying Ydrawings illustratingpreferred embodiments of my invention, and in which'similar referencenumerals refer to similar parts 'throughout the several views;

Figure 1 isa front elevation, with parts brokenaway, of a scaleembodying one form of my lnvention;

Fig. 2 is a transverse sectional view taken substantially on the line2-2 of Fig. 1;

Fig. 3 is a detail front elevation of the springs of a modified form ofmy invention employing a thermostatically actuated means forautomatically increasing or decreasing the effective length of theregulating spring;

Fig. 4 is a side elevation thereof; and

Fig. 5 is a front elevation of the upper portion of ya scale embodying afurther modification of my thermostatically-actuated adjusting means.

This application is filed as a division of my application tiledl\[a;v10,1916.and bearing the Serial Number 96.509 which has eventuatedin Patent No. 1,300,141. dated Apr. 8, 1919.

Referring to the embodiment shown in Figs. 1 and 2 of the drawings. ahollow base 5 supports at one end a column 6 upon which is -mounted acasing T carrying the indicator chart 8 and the spring weighingmechanism ofthe scale. The base 5 is adapted to contain a leveragesystem (not shown) upon which is supported a goods-receiver or platform9, as is common in scales of this character, rand the leverage system isconnected by*the hook-rod l0 with the spring` weighingjmechanism. l Itis to be understood that any suitable platform and platform levermechanism may be employed in connection with the spring weighingmechanism of the scale. the weighing mechanism herein shown beingdesigned to satisfactorily operate when employed in vvarious kinds ofscales, as. for example, portable, scales. 4

The spring. weighing mechanism of the scale comprises: a pair ofload-counterbalancing springs lljconnected at their lower ends to anequalizer bar, 12 which is pivotally connected. asby the link 13, withthe upperend of the hook-rod 10, which, as above described, is connectedat its 'lower end with the platform lever mechanism. The equalizer bar12 also fcarries the rack rod 14 meshing withthe pinion 15 fixed on theindicator shaft 16 'which is suitably mounted in bearings. on theframework 17 and carries at its forward extremity the index hand 18coperating with the chart 8 to dormant and hanging vindicate the weightsof loads placedon the platform 9. rl`he chart 8 is mountedconcentrically of the indicator shaft 16 and is suitably graduated inany desired manner. Any suitable means may also be employed formaintaining effective Contact between the teeth of the rack 14 andpinion 15 in the operation of the scale. rI`he upper ends of theloatl-counterbalancing springs 11 are adjustably connected with across-bar 19, preferably on opposite sides of the center thereof. Theupper ends of the equalizing springs 20 are also connected with the cr0ssbar 19 and are adjustably secured at their lower ends to bracketscarried by the framework 17 of the scale, these equalizing springs 20being of substantially the .same mass as the weighing orcounterbalancing springs 1 1 and of substantially the same length andd1- ameter. The cross-bar 19 is secured to the free ends of laminatedleaf abutment springs 21, the other ends of which are fixed, as shown inFig. 2, upon the framework 17. The springs 21 are of sutiicient strengthand stiffness to normally support the bar 19 and the elements suspendedtherefrom, but the weight of the bar 19 and the elements connectedthereto tend to put the springs 21 under 'considerable tension bybending the abutment springs downwardly, this tendency bet ing augmentedby the tension exerted thereon by the springs 11 and 20.

In the operation of the embodiment illustrated in Ifigs. 1 and 2, aloadplaced upon the platform 9 will exert a downward pull on theequalizer bar 12 through the steel-` yard rod 10, and this downward pullwill serve to elongate theA weighing springs 11, and also to slightlybend in a downward direction the leaf abutment springs 21. Thus, theoffsetting of the weight of the load is distributed between the coilsprings 11 and the leaf abutment springs 21. T he equalizing springs 2Oare not utilized in the weighing operations of the scale, but areemployed solely to correct for changes in temperature, as will be nowdescribed. Supposing the scale to be sealed to a temperature of. sayG50. an increase in temperature will serve to expand and elongate theseveral springs, which` without corrective measures, would affect theaccuracy of the scale. In my improved device the. expansion of theweighing springs 11 and the equalizing springs 20 would be substantiallyequal, and would serve to counteract each other in correcting forinaccuracies due to change in temperature. Thus, the expansion of theweighing springs 11. considered alone, would relieve a portion of thetension intheregulating abutment springs 21 and also allow the equalizerbar 12 to fall a short distance under the weightpf the steelyard rod 10and the pull exerted thereon by the platform lever mechanism. @n theother hand,

the expansion of the equalizing springs 2O would serve to free only theabutment springs 21 from a portion of the tension eX- erted thereon andallow them to move upwardly to `take up thisexpansion.' In thecombination, therefore, the additional upward movement. allowed to theabutment springs 21 because of the expansion of -the equahzing springs20 would yserve to lift the weighing springs 11 and the equalizer bar 12a distance corresponding to that which the equalizer bar would fallunder the eX- pansion of the springs 11. In other words, the expansionof the equalizing springs 20 will serve to sufficiently relieve thetension normally exerted on the abutment springs 21 to permit the lattersprings' to take up any and all expansion in the weighing springs 11 sothat the equalizer bar 1.2 and the rack carried thereby will remain insubstantially their normal positions despite the temperature increase.Contraction of the springs 11 and 20 due to falling of the temperaturewould result similarly-the contraction of the equalizine springs 2()serving to bend the abutment springs 21 downwardly a sufiicient distanceto allow the springs 11 to contract without affecting the normalposition of the equalizer bar and the rack let.

In Figs. 3 and 4 I have substituted a. thermostat and movable abutmentcontacting the laminated abutment springs for the equahzing springs 20of my. first-mentioned modification. The thermostat 22 is rigidlyconnected at one end to a bracket carried by a frame 17b and pivotallyconnected at its other end, as through the link 23, with the lower armof a bell-crank-lever 24 mounted on said frame, the upper arm of whichcarries a roller 25 contacting the laminated abutment spring 21. Theweighing springs 11b are connected at their upper ends to a cross-'bar19b which is suitably ecured t0 'the free end of the laminated spring2lb,

as shown in Fig. 4. The lower ends of the weighing springs 11b areconnected to the equalizer bar 12b which carries the rack 141 and isconnected through the steelyard rod 10b with a suitable goods-receiver.thermostat 22 herein shown is constructed of two metals-jor example,brass and steel, rigidlyvunited, with the former metal on the inside.The shape of the thermostat is preferably that of a horse-shoe in orderto obtain a greater amount of movement therefrom in a limited amount ofspace. I do not intend to limit myself to any particular form ofthermostat, and disclose the thermostat shown merely as one method thathas been found to work satisfactorily in the scale.'

The weighing operation of the embodiment shown in Figs.' 3 and 4 issubstantially identical with that of the embodiment llustrated in Fig.l, the weight of a load being The( . the scale is sealed, the expansionof the thermostat 22 moves "the roller 25 carried by the n lever 24toward the free end'of the spring 21b"so as toplace theabutment rollerfarther from the fixed end ofthe spring, thereby stiffening this springand'raising the free end thereof a distancesufiicient to take up Y theexpansion in the weighing springs 11".. A falling of the temperaturewill' result in i the contraction ofr the thermostat 22 to move theabutment roller 25 towardthe fixedend of the leafspring 2lb, relievingthe tension in said spring and...allowing it to fall sulfi- 4cientlytocounteract for the contraction in the wei hin s rin 11".

The iodiiicaliiongsshown in Fig. -5 illustrates the use of a'singleweighing spring 11 in connection with a single laminated spring 21C. Inthis embodiment I have illustrated an arrangement wherein a thermostat22 of substantial length may be compactly employed ina scale, saidthermostat having one end 'fixed to a bracket 17 c carried by the casingofthe scale and then encircling the pinion 15c andcthe rack and havingits other endconnected,l as by the vlink 23,"With a bell-crank-lever 24havin its end formed as a curved abutment 26. uring temperature lchangesthe `thermostat22c will serve to move theabutment 26 towardy or awayfromthe fixed end o f the laminated spring 21, thereby lvarying vthetension in vand raising or lowering the pring 21. to allow for theexpansion or contraction of the weighin spring 11.

a ile the embodiments herein illustrated disclose constructionsl wellada ted to adei' ('Jounterbalance` spring,` connections fromv the` lowerend iof the' counterbalance spring to the'goods-receiver, a regulatingabutment 'in' accordance with spring fixed at one end upon the scaleand" havingits op site end connected to-tllief'upper end oft ecounterbalance springl and` normally lheld under tension thereby,.affidi -thermostaticallyactuated means engagin the abutment springadjacent its point o engagement with the counterbalance spring. forvvarying the tension of said abutment spring in accordance withtemperature changes', said means including a lever arranged to 4be movedalong the `abutment spring.'v 2. n a spring scale, a goods-receiver, a

counterbalance spring, connections from the lower end of thecounterbalance spring to the goods-receiver, a regulating abutmentspring fixed at one end upon the scale and having itsl opposite endconnected to the upper end of the counterbalance spring and normallyheld under tension thereby, a thermostat, and a lever having one armconnected to the thermostat and its other arm in engagement with theabutment spring, whereby the tension of said abutment spring may bevaried in accordance withl tempera- `ture changes.

3. In a spring scale, a goods-receiver, a

counterbalance spring, connections from the lower end of thecounterbalance spring to'` Vvthe goods-receiver, a regulating abutmentspring fixed at one end' upon the scale and having its opposite lendconnected to the upper end of the counterbalance springjand normallyheld und'er tension thereby, a ther- 7mostat, and a bell-crank-leverhaving one arm connected to the thermostat land its other arm'inengagement with the abutment spring whereby' lthe tension of saidabutment spring may be varied in accordance with temperature changes. l

4. In-a spring scale, a goods-receiver, a

counterbalance spring, connections from the lower end of thecounterbalance' spring to the kgoods-receiver, a regulating abutmentspring fixed at one end upon the scale and having its opposite endconnected to the upper end ofthe counterbalance spring and L normallyheld under tension thereby, a lonf gitudinally-curvedthermostat; and abellcrank-lev'er having one arm connected to the thermostat and .itsother arm in enga ement with the abutment spring, whereby t e ten-` sionof said abutment spring fm'ay be; varied tem erature chan es. A.

l H NRY'ED Nr. Witnesses:

ANNA M. MATER, B. D. Anrnnnrmmn.

